I am trying to remove the "Created By" and "Last Modified By" text from the pitch form, but when I press the minus button to remove them, they appear again in the "Fields" box. How do I correct this?

Sorry you're stuck but there's almost always a pretty easy fix! Do NOT try to start all over again, uninstall Max's Pitch Package, etc. That can make it worse. There's a 95% chance the same snag/fix is listed & answered in the Help FAQ. But if you can't find it there, post your problem here.
Make sure you post in the right category below & be sure to include a screencap showing the issue!
Yeah, it's ok that they appear in the fields box after you remove them from the layout. That's where they reside until you drag them into a layout.